Known dip coating is by immersing the item to be coated in a bath consisting entirely of the coating and moving the item out of the bath. A meniscus naturally forms between the bath and the item, and a coating of the bath material clings to the item. To coat, for example, a cylinder, the cylinder is oriented with its long axis vertically and is moved down into the bath and then upward out of the bath. As it leaves the bath, it is coated with the bath material.
Where the bath chemically deteriorates with the passage of time or by contamination from items immersed or the atmosphere, it is discarded and replaced by a new bath. This invention may employ standard coating apparatus but significantly limits the amount of bath material which is subject to such discharge. This invention employs a ring of coating material floating on a column of noncoating material. Example 1 of U.S. Pat. No. 5,683,742 to Herbert et al. has a film of coating material sprayed on water.